AGING AND GAIT Flashcards
Aging and Postural control
-over 65 yo: 1 of 3 experience a fall per year
—>falls are leading cause of injury deaths
—>falls are leading cause of disability and decreased independence
-20-30% sustain injury that reduces mobility
Why do falls increase as we age?
-decreases in cognitive function, sensory function, and motor function
-if all three of these functions decrease below a certain threshold –> much greater fall risk (functional limitation threshold)
-may see falls earlier on if you have a challenging task and/or environment that challenges cognition
-a combination of factors contribute to increase in falls as we age: disease, environment, genetics
Skeletal changes in bone with aging:
*Shape and density altered with the balance of resorption and formation of bone
*Decline in bone mass with age
*Decreased tolerance for stress
*Altered joint motion- due to changes in joint surfaces
Joint changes with age
-decreased ROM at most joints
-active decreased more than passive due to ms. tendon unit
-increased stiffness due to viscoelastic changes –> changes in water content (more stress for certain level of strain)
-passive ROM may be limited due to stiffness
-greater demand moments are required for movement
Muscular changes with age:
sarcopenia: Age- associated decline in muscle mass due to total number of fibers decreasing
-begins at age 30
-gradual loss of muscle mass from 30-50 yr
-30% loss from 50-80 years
How does muscle change with age when torque (moment) production is normalized to the cross-sectional area or mass?
small age-related decrement remains
-there is a general increase in weakness that occurs with aging
Neuromuscular changes with aging:
OLDER ADULT CHANGES:
-initially lower number of fibers recruited
-fiber recruitment variable over time
-can achieve same levels of firing with practice
-proximal recruitment greater than young adults
-distal recruitment in older adults is less compared to younger
-decreased CSA of type II (fast twitch)> type I (slow twitch) –> more a blend of type I and II
-increased co-activation of mm. may lead to decreased effective moment production –> decreased efficiency of gait (have to produce more force to achieve same gait speed)
Strength, power, and endurance changes with aging:
STRENGTH: Declines 10-15% per decade after fifth decade
POWER: moment * angular velocity
-declines similar to strength
-more closely correlated with functional ability
-loss appears earlier than strength and more rapid decline
Sensory changes with age
SOMATOSENSORY
* Decreased proprioception, tactile sensitivity, vibration sense
(peripheral neuropathy)
VISION
* Decreased acuity, visual threshold (light needed), and contrast
sensitivity
VESTIBULAR
* Decreased hair and nerve cells
changes in older adult gait
-dec. gait speed
–> if ankle PFs are more weak: step length decreases
-dec. stride length: to reduce loading force through the limb, to decrease SL support time
-dec. SLS time
-altered joint kinematics (ankle largest)
-increased step width variability
-increased energy expenditure
What is the typical range for gait speed from ages 20-59?
1.35-1.4 m/s
What spatiotemporal aspect of gait does not change much in older adults?
cadence- step frequency
steps taken/minute
Kinematics at each joint change with age–> why is this important?
change in kinematics is expected with change in speed
kinematic change at the same speed is what is important
Change in joint kinematics with age
-hip extension reduced with age (38% decrease)
-knee motion stays relatively the same with age
-ankle plantarflexion motion decreases with age
-ankle DF decreases about 43%
-more anterior pelvic tilt in older adults
Older adults have to expend more energy to walk at the same _____ as younger adults
speed
Reasons for older adult gait changes:
-desire for increased stability (increased DL support time)
-impaired body structure and function
-desire to limit force absorption at the joints
-maximizing walking economy
—> decrease gait speed to decrease amount of energy expenditure
-change in motor pattern –> distal muscles lose function more quickly and proximal muscles increase their action to compensate for distal loss
Can decreased ROM caused by age-related changes improve with exercise?
yes
-shown increases in hip extension and ankle dorsiflexion
What LE muscles have a decrease in power and what LE muscles have an increase in power with age?
HIP
-power increases with age
KNEE
-slight decrease in power in older adults
ANKLE
-ankle power decreases significantly with age
-greatest difference in power between older and younger adults
Phases of gait in weight acceptance
initial contact
loading response
Phases of gait in single limb support
mid stance
terminal stance
phases of gait in swing limb advancement
pre swing
initial swing
mid swing
terminal swing
Is power or strength training more beneficial functionally for older adults?
power training
Individual intervention for older adults to decrease effects of aging process:
FLEXBILITY/ROM
-ankle
-hip
-trunk
STRENGTH
-distal especially
-ankle plantar flexors
-neuromuscular coordination
-proprioception training
-postural education
-attention
-activity level
